1. Field of the Invention
The present invention relates to a tube capping assembly for use with a centrifuge tube and, in particular, to a tube capping assembly which includes a crimpably deformable element.
2. Description of the Prior Art
During a centrifugation run a sample container that carries a liquid sample of a material under test is exposed to forces which range up to several hundred thousand times the force exerted due to gravity. Accordingly, extreme care must be exercised in the design of sample container closure systems in order to withstand this extreme operating environment.
When open mouth test tube-like sample containers are utilized closure members for these containers typically include a central portion which projects inwardly into the mouth of the sample container. The central portion acts against the upper end of the sample container to urge the same into compressive contact with an outer cap. Typically further, the cap assembly may be threadedly secured into the body of the ultracentrifuge rotor to maintain the sealed integrity of the interface so established. Exemplary of such open mouth sample closure systems are those shown in U.S. Pat. No. 3,635,370 (Romanauskas), U.S. Pat. No. 4,166,573 (Webster), U.S. Pat. No. 4,190,196 (Larsen) and U.S. Pat. No. 4,222,513 (Webster et al.), all of which are assigned to the assignee of the present invention.
Closure assemblies for open mouth threaded bottles have also been used in confining a sample under test within the interior of the bottle. Exemplary of such devices are those shown in U.S. Pat. No. 3,366,320 (Cho).
The prior art also discloses an arrangement whereby a separate closure assembly for the sample container is not required. Exemplary of such an arrangement is a sample container such as that disclosed in U.S. Pat. No. 4,301,963 (Nielson). Such a container is heat sealable in the manner disclosed in U.S. Pat. No. 4,291,964 (Ishimaru).
Each of the above mentioned techniques of closure of the sample container has certain perceived disadvantages. For example, the closure assembly adapted for use with an open mouth test tube-like container is often relatively complex and time consuming to use. Threaded closure arrangements are prone to leakage. Heat sealing techniques suffer the perceived disadvantage of exposing the sample under test to the potentially harmful effects of the heat when the container is sealed.
Accordingly, it is believed advantageous to provide a separate capping assembly for a sample container which, once a seal for the container is effected, maintains the sealed integrity so established despite exposure to the extreme force fields attendent with ultracentrifugation. Moreover, it is believed advantageous to provide a capping assembly which does not use heat fusion and thereby avoids the potentially deleterious effects that are entailed by the exposure of the sample under test to the heat necessary for fusion of the container.